1. Field of the Invention
The present invention relates to a method for formatting optically encoded digital data in and along tracks on a substrate and the date record carrier formed thereby. More specifically, the present invention relates to the formatting of information about the data on the data record carrier in a first or zero track and then formatting the data itself in successive tracks on the data record carrier. The tracks are preferably arcuate tracks of equal radii that are arranged in a nested array of tracks equally spaced from one another on the substrate.
2. Description of the Prior Art
Heretofore it has been proposed in U.S. Pat. No. 4,213,040 to encode digital information in rows and columns on a record carrier. Data is read from the record carrier by movement of the record carrier on an X axis and rotation transport mechanism which is operable to make skew corrections.
Also heretofore various optical encoded data record carriers and optical "writers" and "readers" have been proposed. For example, in U.S. Pat. No. 3,549,897 there is disclosed an absolute electro-optical encoder for indicating the angular position of a shaft. The encoder includes a stationary disc and a rotary disc, the discs having concentric tracks with transmissive and non-transmissive portions which are binarily related. Light passing through the discs is picked up by certain selected combinations of photocells for indicating the position of one disc relative to the other disc.
In U.S. Pat. Nos. 3,501,586; 3,624,284; 3,885,094; 3,795,902; 3,806,643; 3,891,794; 4,090,031 and 4,163,600 issued to J. Russell, various "writers" and "readers" are disclosed for "writing" digital data on a spiral track and for "reading" digital data from the spiral track. In the optical encoding and decoding systems described in these patents opaque spots on the track correspond to logic 1 bits of binary data and transparent spots on the track correspond to logic 0 bits of binary data. Also, larger synchronization spots are provided at different places along the track.
An apparatus for scanning a data record medium is disclosed in U.S. Pat. No. 3,898,629 wherein binary digital information is recorded in the form of data along a circular arc and a plurality of such circle arcs of data information are arranged tightly adjacent each other.
In U.S. Pat. No. 3,919,697 there is disclosed a data record having track lines which may be separate parallel tracks or may be a single series track of the spiral or raster type.
In U.S. Pat. No. 3,983,317 there is disclosed an astigmatizer for a laser recording and reproducing system. In this system concentric circular tracks are formed in a thermoplastic record or disc by burning selected holes through the disc with a laser. The laser is "on" while the disc is being rotated a short distance to form an elongate data information bit in the track. Then, in reading the data the laser beam or spot is elongated in a direction transverse to the direction of the track with an astigmatizer unit so that a small elongate beam of light with an axis extending transverse to the axis of the track and of the elongate opening therein is used to read the opening.
In U.S. Pat. No. 4,094,010 there is disclosed an optical multi-channel digital disc storage system. Data is stored on a spiral information track and holes corresponding to the information data are burned into the material of the disc by an information radiation beam.
U.S. Pat. No. 4,094,013 discloses an optical storage disc system with disc track guide sectors wherein the data tracks are spiral shaped turns or concentric turns on the disc. The data stored is again in the form of holes burned into the disc.
U.S. Pat. No. 4,209,804 discloses a record carrier containing information in an optically readable radiation reflecting information structure. With the record carrier of this patent, data is stored in a spiral track on a disc in the form of information areas comprising pits pressed into the record carrier surface or hills projecting from the record carrier surface. According to the teachings of this patent, the depth of the pits or the height of the hills is constant and so is the width of the information areas and intermediate areas at the level of the plane of the lands. Then the information to be conveyed by the record carrier is contained in the variation of the structure of the areas in the tangential direction only. More specifically, the information areas are substantially V-shaped, the phase depth of each information area having one value between 100.degree. and 120.degree. and the angle of inclination between the walls of the information areas and normal to the record carrier are substantially constant and have a value between 65.degree. and 85.degree..
As will be described in greater detail hereinafter, the present invention differs from the record media and carriers disclosed in the prior art patents referred to above by providing a method for formatting optically encoded binary/digital data in tracks on a substrate of a record carrier and the data record carrier formed thereby. In particular, each track of data has a leading end comprising a leader section and front track address section at the beginning of the track and a tail end comprising a back track address section and a tailer section at the end of the track. The tail end of each track is a mirror image of the leading end of the track. That is to say, the tailer and back track address sections are a mirror image of the leader and front track address sections.
Moreover, in accordance with one aspect of the present invention, a plurality of coded groups of digital data containing information carried by the data record carrier are positioned in each track between the front track address section and the back track address section.
Furthermore in accordance with another aspect of the present invention, the first or zero track has coded groups containing information that is only read by a computer associated with a reader or scanning device.
By formatting the tracks with a tail end which is a mirror image of the leading end and by storing data on the tracks in coded groups, one can easily find out which track is being read by a reader or scanning device and with the data being coded, a "best guess" can be made of any data that may be missing due to an error, such as a "burst error" in the data on a track in the data record carrier such as a burst error caused by a hole punched through the data record carrier.
Also, a plurality of the arcuate tracks of the cells are created on a substrate with each track being spaced from an adjacent track by a predetermined distance at a point intermediate the ends of each track, and each track has the same radius throughout the arcuate path of the track such that the tracks extend in an arcuate manner across the data record carrier with each track having the same radius and being arranged in a nested manner relative to adjacent tracks along a common centerline.